Time delay switch



Dec. 15, 1964 M. K. BETHUNE TIME DELAY SWITCH Filed March 15, 1962 INVENTOR. MANNING K BETHUNE a B iwiy Q United States Patent 3,161,734 TIME DELAY SWHTCH Manning K. Bethune, Rochester, NY, assignor, by mesne assignments, to the United States of America as represented by the Secretary of the Navy Filed Mar. 15 1962, Ser. No. 18%,061

3 Ciaims. (Cl. Nit-38) This invention relates generally to mechanically controlled timing devices for and more particularly to a clutter retarded gear train mechanism for mechanically effecting a delay in an electrical switch.

In this invention a clutter retarded spring driven, threaded drive shaft is employed to move a timing nut into a position for opening or breaking an electrical contact after a predetermined time interval. With the arrangement of this invention an electrical switch or contact may be operated at a predetermined time ranging from zero to 60 seconds with 10% tolerance. The mechanism of this invention is designed to operate after relatively long exposures to vibrations of 50 to 2,000 cycles per second with forces up to 12.5 g. applied thereto. In actual operation, forces up to 30 g. may be applied along the axis of the drive shaft. The mechanism is energized by a power spring that will operate without loss of accuracy after exposure to extreme environmental conditions.

An object of this invention is to provide a timing device for closing an electrical contact after a predetermined time delay.

Another object of this invention is to provide a clutter retarded spring driven threaded shaft having a nut thereon to actuate an electrical switch.

A further object of this invention is to provide a spring driven delay mechanism for operating an electrical contact at a predetermined time interval after unlocking said mechanism.

A still further object of this invention is to provide a clutter retarded, spring driven mechanism that will operate an electrical switch from zero to 60 seconds after the release of a locking lever.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference of the following detailed description when considered in connection with the accompanying drawing in which like reference numerals designate like parts throughout the figures thereof and wherein:

FIG. 1 of the drawing illustrates the unwound or armed position of an embodiment of the timing mechanism of the invention; and

FIG. 2 illustrates the Wound or unarmed position of an embodiment of the timing mechanism of this invention.

Referring now to FIG. 1 of the drawing in which armed position of the timing mechanism is illustrated and to FIG. 2 of the drawing in which the unarmed position of the timing mechanism is illustrated, timing mechanism 11 contains gear train 13 connected to threaded shaft 15. Threaded shaft 15 is provided with a threaded nut 17 having a lug portion 18 which is restricted from rotation by a channel groove 19 in member 21. A power spring 23 is connected to threaded shaft 15 to provide a source of energy for rotating threaded shaft 15. Threaded shaft 15 has a squared end portion 25 providing for a key or other means to wind up the power spring 23. A contact plate 27 is grounded and fixed at one end by bolt 22? and adapted to contact terminal 31 at the other end which is free. An adjusting screw 33 is mounted in a the contact plate near the free end by threadable engagement with nut 34 which may be secured to contact plate 27 in any suitable manner. The lower end of adjusting screw 33 is located for contact with lug portion in of threaded nut 17. Contact plate 27 is provided with a cut-out portion where shaft 15 passes through the plate such that there will not be an electrical contact between the contact plate and the shaft. Adjusting screw 33 has a slotted up per end portion to provide for engagement with a screw driver for raising or lowering the screw to vary the position at which the lower portion of the screw will come in contact with the lug 18 of threaded nut 17. A spring loaded locking lever 35 is adapted for engaging a flat portion of shaft 37 to lock the gear train and prevent shaft 15 from rotating. Locking lever 35 is also adapted for engagement with slide 33 through roller 39. Slide 38 is provided with a shoulder 41 for engagement with slide stop catch 43 which is secured to the frame of the timing mechanism. A terminal connection 45 is mounted on slide stop catch 43 which is grounded or connected to the frame of the timing mechanism. Terminal 31 is connected to wire 47 and insulated from the frame of the timing mechanism. When the timing mechanism is in the armed position, that is when timing nut 18 it at the top of its travel, as shown in FIG. 1, the contact plate will be out of contact with terminal 31 and there will be an open circuit between wires 47 and 49. When the timing device is in the unarmed position, as shown in FIG. 2, there will be a closed circuit between wires 47 and 49;

In operation, the timing nut before winding will be in the upper position as shown in FIG. 1. When power spring 23 is wound up, the timing nut 17 will be at the bottom position of its travel and power spring 23 will be compressed. A spring 22 presses against the timing nut to prevent lost motion between the timing nut and the threaded shaft. When power spring 23 is wound up, it is prevented from releasing energy through gear train 13 and unwinding by locking lever 35 which is pressed against a flat portion of shaft 37 by spring 53, preventing shaft 37 from rotating and preventing the movement of the gear train. The timing device is now in the unarmed position as shown in FIG. 2.

The gear train may be unlocked by moving locking lever 35 away from shaft 37 allowing the gears to rotate. This is done by moving slide 38 until slide stop catch 43 engages the shoulder 41 of the slide and lever 35 is held in the position shown in FIG. 1. The spring is now free to re lease its energy through gear train 13 causing shaft 15 to rotate and causing timing nut 17 to move to the top of the shaft, moving contact plate 27 upward, as viewed in the drawing, when the lug portion 18 of nut 17 comes in contact with adjusting screw 33. The upward movement of contact plate 27 breaks the contact with terminal 31 and the electrical contact between wires is opened, placing the device in the armed position.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood, that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

l. A timing mechanism for breaking an electrical circuit after a desired delay time comprising a clutter retarded gear train, a power spring connected to said gear train and adapted to operate said gear train when said spring is wound, locking means on said gear train for locking said gear train, a threaded shaft connected to said gear train, said shaft being rotated by said gear train when said gear train is operating, a threaded nut mounted on said shaft, means restricting said nut from rotation such that said nut will travel along said shaft when said shaft is rotating, a contact plate normally connected to a terminal at one end and grounded at the other end, whereby an electrical circuit is closed, said contact plate having an adjustable screw contacting said nut as said nut travels along said shaft, said screw adjustable to contact said nut at a preselected position along the travel distance of said nut, said nut operable to open the contact between said contact plate and said terminal when said nut contacts said adjustable screw.

2. A time delay mechanism for operating an electrical switch after a predetermined time interval comprising a threaded shaft, power spring means connected to said shaft to apply rotational energy to said shaft, a gear train connected to said shaft to regulate the rotation speed of said shaft, locking means in said gear train for keeping said shaft stationary, releasing means for releasing said locking means whereby said shaft is free to rotate, a threaded nut on said threaded shaft, a housing for said time delay mechanism, a groove in said housing parallel to said threaded shaft, a lug portion on said threaded nut, said lug portion of said nut slidably engaging said groove such that said nut is restrained from rotation, said nut adapted to move along said shaft toward the top of said timing mechanism as the shaft is rotated by said power spring, a contact spring mounted on the top of said housing, said contact spring being fixedly connected and grounded to said housing at one end and being spring biased against an insulated terminal at the other end of said spring contact such that an electrical circuit is closed through said spring contact, said spring contact having a hole therein, said threaded shaft projecting through the hole such that said nut will push against said spring contact and move it from said insulated terminal, opening said electrical circuit as said nut approaches the top of said housing when said shaft is rotated, and means adjusting the position at which said nut will push against said spring contact.

3. Time delay means for actuating an electrical contact to break a circuit comprising, a frame, a contact spring mounted horizontally on the top of said frame, means fixedly connecting one end of said contact spring to said frame with the other end of said contact spring biased against an insulated terminal, a grounded terminal electrically connected to said contact plate through said frame, a rotatable threaded shaft mounted vertically within said frame and adapted to be rotated, a threaded nut on said shaft, means causing movement of said nut from the bottom of said shaft to the top of said shaft as said shaft is rotated, a power spring connected to said shaft for rotating said shaft, a gear train connected to said shaft for regulating the speed of rotation of said shaft when said shaft is rotated by said power spring, locking means in said gear train for keeping said shaft stationary, releasing means for releasing said locking means whereby said shaft is free to rotate, said contact spring having a hole therein whereby said shaft projects therethrough, said nut operable to press against said contact spring and move said contact spring away from said insulated terminal thereby breaking an electrical circuit, and means adjusting the position at which said nut presses against said contact spring whereby the delay time may be varied.

References Cited by the Examiner UNITED STATES PATENTS 2,870,288 1/59 Schmidt 200-158 2,946,863 7/60 Holzer 200-35 2,946,902 7/ Hagen 20038 2,951,920 9/60 Miller 200-47 3,022,390 2/62 Cline t a1. 200-38 BERNARD A. GILHEANY, Primary Examiner.

ROBERT K. SCI-IAEFER, Examiner. 

1. A TIMING MECHANISM FOR BREAKING AN ELECTRICAL CIRCUIT AFTER A DESIRED DELAY TIME COMPRISING A CLUTTER RETARDED GEAR TRAIN, A POWER SPRING CONNECTED TO SAID GEAR TRAIN AND ADAPTED TO OPERATE SAID GEAR TRAIN WHEN SAID SPRING IS WOUND, LOCKING MEANS ON SAID GEAR TRAIN FOR LOCKING SAID GEAR TRAIN, A THREADED SHAFT CONNECTED TO SAID GEAR TRAIN, SAID SHAFT BEING ROTATED BY SAID GEAR TRAIN WHEN SAID GEAR TRAIN IS OPERATING, A THREADED NUT MOUNTED ON SAID SHAFT, MEANS RESTRICTING SAID NUT FROM ROTATION SUCH THAT SAID NUT WILL TRAVEL ALONG SAID SHAFT WHEN SAID SHAFT IS ROTATING, A CONTACT PLATE NORMALLY CONNECTED TO A TERMINAL AT ONE END AND GROUNDED AT THE OTHER END, WHEREBY AN ELECTRICAL CIRCUIT IS CLOSED, SAID CONTACT PLATE HAVING AN ADJUSTABLE SCREW CONTACTING SAID NUT AS SAID 